In order to reproduce:
I can not reprofuce it :(

@akosyakov I can't reproduce it either, I see the command palette even when an editor is maximized.
I tried with Chrome and Firefox browser and electron on Ubuntu 16.04, I cannot reproduce it either, the quick palette is always available.
Note: I always keep the Chrome toolbar available in my environment
I can reproduce it in Gitpod prod, but not with vanilla Theia. Although Gitpod does not have any specific in this area, strange :(
@akosyakov tested lately in Gitpod and the issue does not persist :)
Ok, feel free to close
Thanks @akosyakov :)